RE-EVALUATION OF EXISTING FATIGUE CODES IN EUROCODE 3.1-9

Abstract

Steel structures are being built worldwide for more than 120 years. The effects of repetitive loading i.e. fatigue on steel structures such as bridges or towers have been extensively studied since the 1960s. The work and lessons learned from the poor performance of some structures have led to the better understanding of fatigue behavior. In 1985, consequent appearances of the first European Convention for Constructional Steelwork (ECCS) recommendations on fatigue design have changed the spirit radically. At European level, the ECCS recommendations contains first unified fatigue rules, followed by the development of structural Eurocodes. Eurocode 3 defines values of fatigue strength for particular structure on the basis of which designing of the structure is being carried out since last 58 years. However, many factors have improved over these years like quality and consistency of material and its properties, improvement in welding techniques, and reliable testing data. So an important initiative is undertaken by research community in Europe to redefine the pre-existing fatigue values. The initiative is based on the fact that the earlier analysis was done considering a high factor of safety or with low confidence limit. In view of this present work was planned to study the” Existing Fatigue Codes in Eurocode 3.1-9”and its Re- Evaluation by applying statistical approach on the available data. Efforts were made to collect existing fatigue data on Eurocode 3.1-9 Fatigue Classes. The background document available in this regard was thoroughly analyzed in order to find out the efficacy of the existing fatigue classes in Eurocode 3.1-9. In the process of such analytical activities, the existing data will be appropriately classified for their best relevance to applications. Statistical approach has been applied on the collected data to know the value of fatigue by doing the analysis for 95% survival probability at 2 million cycles by making use of prediction interval. Also, the addition of two more codes in EC 3.1-9 has been recommended after doing the study on one more code given by International Institute of Welding (IIW) named as “Recommendations for fatigue design of welded joints and components”.